28 July 2025
Yesterday morning was so muggy that Charity Kheshgi and I went to Duck Hollow hoping for a cool breeze. Even at the water’s edge there was very little breeze but there were cool flowers.
From a distance American water willow (Dianthera americana) looks like common green stuff growing at the water’s edge. Through binoculars I could see that Duck Hollow has a lot of it, even more than marked on this photo.
Water willow has to have its feet wet.
The creeping rhizome allows Dianthera americana to form large colonies on or near the shorelines of still or slow waters in lakes and rivers, and on rocky riffles and shoals in faster flowing rivers. Its rhizomes and roots provide important spawning sites for many fish species and habitat for invertebrates.
— Wikipedia: American Water Willow
The leaves resemble willow but unlike real willows this plant never gets more than three feet tall. Its dense vegetation and rhizomes help reduce shoreline erosion.
From a distance the small white and purple flowers, only 1.5 inches across, are difficult to see. Up close they are beautiful, almost like irises, and their purple markings lure in pollinators. The clump we examined was humming with honeybees, shown at top.
We also saw a tiny new-to-us moth. iNaturalist suggested an orange-banded Tripudia moth (Tripudia flavofasciata) which is “expected nearby.” Is that what it is?
If you live near water in eastern North America chances are good that you have water willow near you. Blooming from summer to fall it is common within its wide range.
If this is Tripudia balteata then you not only could have a first PA record, but also for the Northeast. This moth is found in southern California to Texas. A few have been found in South Carolina.
Nice find.
Bob
Bob, iNaturalist suggested Tripudia flavofasciata and said it was “expected nearby”
(not the Tripudia balteata you mentioned)